COLUMBIA - The South Carolina Republican Party is demanding that a third party candidate running for governor stop referring to himself as a Republican in campaign advertising.

Independent Tom Ervin, a former judge and S.C. House Democrat in the 1970s, had originally filed to run against Gov. Nikki Haley in June's Republican primary. But he opted to jump out of the primary and instead run as an independent.

In Ervin's recent campaign advertisement, the words "independent Republican" flash under his name. A lawyer for the state party, Doug Smith, wrote in a letter to Ervin on Thursday that his use of the word is misleading and illegal under campaign rules. "Tom, my days in your court, while many years ago, tell me that you are not about misleading the public, however this does," Smith wrote. "(P)lease cease and desist from the use of the word 'Republican' in your campaign advertising."

The GOP cites a 1961 New York state case that they say established the rule.

Columbia lawyers said that the GOP's case was weak, calling it a First Amendment issue. "There is no DNA testing to determine party affiliation," said Jay Bender, a lawyer who represents media organization around the state, including the Post and Courier.

Chris Kenney, a lawyer who is not affiliated with a campaign and works for Democrat Dick Harpootlian's law firm, said it's not a case that would have much of a chance in court. The 1961 case from another state likely wouldn't be upheld under the First Amendment right to free speech, he said. "If they were to pursue a challenge I think that they would be laughed out of court," he said.

Ervin said that the statement is a truthful one and that he has long been a Republican, including hosting a fundraiser for GOP presidential candidate Mitt Romney at his Greenville home. He has no plan to pull his advertisement.

"They're worried," he said of Haley's campaign. "We have freedom of speech in this country and it's a truthful statement. I've got every right to call myself a Republican because I am a Republican."

Matt Moore, chairman of the S.C. Republican Party, said at a Thursday press conference that Ervin had his chance for the GOP's backing.

"He had a chance to run in a primary," he said. "As a former judge, Mr. Ervin should know better."

Ervin was a surprise entry into the race, first into the GOP primary and then as an independent on the ballot in November when he dropped out weeks later. Charleston Libertarian Steve French has also entered the race, and Democratic candidate Vincent Sheheen does not have any primary opposition.

Experts say that it will be tough for any candidate to beat Haley, a Republican incumbent who has touted an improving economy and state employment gains in her bid for a second term.

Haley defeated Sheheen by less than five percentage points in 2010.

Democrat Joe McCulloch, a Columbia lawyer who is running for the state House of Representatives, said Democrats enjoyed the fact that Republicans were going after each other.

"From a legalistic standpoint, impersonating a Republican is not a criminal offense," he said. "It's interesting to watch the party eating its own."

Reach Jeremy Borden at 708-5837.